Secondary and Micronutrient Management Kent Martin Southwest Area Crops and Soils Specialist Kansas State Univ.

Essential Nutrients Thirteen essential nutrients Nitrogen, phosphorus, potassium, calcium, magnesium, sulfur Iron, manganese, boron, molybdenum, copper, zinc, and chlorine Nickel has recently been added Micros are needed in much lower concentrations to ensure adequate supply

Essential Micronutrients Minor elements or trace elements Increased interest in micronutrients Higher crop yields and micronutrient removal rates Declining soil organic matter, a major source of most micronutrients N, P and K fertilizers contain lower amounts of micronutrient impurities Excessive levels can cause toxic effects on plants In Kansas: S, Zn, Fe, and Cl. Other micronutrients: B, Mg, Cu, Mn, and Ni.

Organic Matter Important source of most micronutrients. Simple organic compounds as chelates. S, Zn and B deficiencies are more likely to occur in soils low in O.M. Deficiencies of Cu and Mn are most common in peat soils.

Soil pH Soil pH affects availability of micronutrients. In general the solubility and availability of micronutrients are greatest in acid soils and lowest in high pH calcareous soils. Exception is Mo. In some soils, high levels of soluble Fe, Al and Mn may be toxic to plants.

Sulfur (S) Brian Lang, IA

Sulfur Deficiencies Soil Situations and Climatic Conditions Aggravating Deficiency Symptoms Coarse textured soils (sandy soils) Low organic matter soils Cold, wet soils Slow release of S from organic matter Low atmospheric deposition No application from Manure Other fertilizers

Sulfur Deposition 10 kg SO4/ha = 3 lb S/acre

Corn Response to Sulfur J. Sawyer, 2007

Corn Response to Sulfur Application Comparison of Corn with and without Sulfur Application. Brian Lang

Sulfur in the Soil Subsoil S may be significant. Profile soil test for S, 0-24 inches, also good for nitrate and Cl.

Sulfur Fertilizer Recommendation Wheat S Rec. (Lb/A) = (0.6 × Y Goal) – (2.5 × % OM) – Profile Sulfur – Other Sulfur Credits Corn and Sorghum S Rec. (Lb/A) = (0.2 × Y Goal) – (2.5 × % OM) – Profile Sulfur – Other Sulfur Credits Soybean S Rec. (Lb/A) = (0.4 × Y Goal) – (2.5 × % OM) – Profile Sulfur – Other Sulfur Credits

Zinc (Zn)

Zinc Frequently deficient micronutrient Absorbed by plant roots as Zn++ Involved in the production of chlorophyll, protein, and several plant enzymes Deficiency symptoms Most distinctive in corn with new leaves out of whorl turning yellow to white in a band between the leaf midvein and margin

Zinc Deficiencies Sensitive crops Corn, sorghum Soil Situation Low organic matter, high pH (>7.4), eroded soil Coarse texture, restricted rooting High P application in conjunction with borderline or low zinc availability High soil P alone does not create deficiency Climatic Conditions Cool and wet soil

Kansas State University Phosphorus and Zinc Excessive concentrations of P in the plant root result in the binding of zinc within root cells. Large amounts of starter applied P can enhance Zn deficiency if soil Zn is low and no Zn fertilizer is applied. P2O5 Zn Yield Leaf tissue lb/A * bu/A P, % Zn, ppm 101 0.14 12 10 102 0.16 24 80 73 0.73 162 0.41 17 Corn is highly sensitive to zinc (Zn) deficiency. High P availability can induce Zn deficiency in soils that are marginally Zn deficient. In this example from Kansas, band applying P without Zn made a Zn deficiency worse than by broadcasting the P without Zn. The corn in the background received 10 lb/A of Zn with P, and this corrected the deficiency. The soil in this example was low in both P and Zn. (Adriano and Murphy). When plants are Zn deficient, their ability to regulate P accumulation is severely impaired. As a consequence, P absorbed by the roots accumulates in excess in the shoot (as can be seen in the data above for the Kansas example). The negative interaction between the two nutrients appears to occur in the plant, not in the soil. Zinc and phosphate can react in the soil to form zinc phosphate, but its solubility is usually sufficient to provide adequate Zn to plants. (Havlin et al., 1999). Data source: Adriano, D.C. and L.S. Murphy. 1967. Phosphorus-zinc fertilization of corn. Kansas State University, Kansas Fertilizer Handbook. pp. 68-71. Havlin, J.L., J.D. Beaton, S.L. Tisdale, and W.L. Nelson. 1999. Soil Fertility and Fertilizers. Sixth edition. Prentice Hall, Upper Saddle River, New Jersey 07458. Adriano and Murphy Kansas State University

P and Zn Effects on Corn Yields P2O5 Zn   B’cast Starter Lb / A Corn Yield (Bu/A) 107 10 121 115 40 93 139 140 St. Mary’s, KS – Kansas State University

Zinc Fertilizer Recommendation Corn, Sorghum and Soybeans Zinc Recommendation Zn Rate = 11.5 – (11.25 × ppm DTPA Zn) If DTPA Zn > 1.0 ppm then Zn Rec = 0 If DTPA Zn <= 1.0 ppm then Minimum Zn Rec = 1

Zinc in a Band—Corn Yield Zn Rate (lb./acre) Yield (bu./acre) 62 0.1 131 0.3 137 1.0 140 3.0 142 Used 8-20-0 suspension with 2.5% clay DTPA extractable Zn = 0.3 ppm

Corn Yield—Zinc Source bu./acre EDTA 136.6 Nulex-Zn 134.8 Zinc Oxide 127.5 Zinc Sulfate 138.3 Zinc rate was 0.3 lb. Zinc /acre

Application Methods Broadcast Band Preferred to correct a low Zn soil test 5 to 15 pound will increase soil test for a number of years Inorganic Zn is more economical than chelates at these rates Band Very efficient method of applying Zn 0.5 lb Zn/Acre of inorganic Zn is generally sufficient Annual applications will be needed for low testing soils

Chloride (Cl)

Chloride (Cl) Wheat, corn, sorghum deficiencies in Kansas Deficiencies most likely in higher rainfall areas with no K application history - central and eastern part of state Soluble, mobile anion Addition of KCl Increased yields with high levels of available K Reduced incidence of plant disease Internal water relationships, osmotic regulation, enzyme activation and other plant processes

Chloride Fertilization on Corn in Kansas Grain Yield Chloride Riley Co. Brown Co. Osage Co. Rate Site A Site B Site C lb/a - - - - - - - - - - - - - - - - bu/a - - - - - - - - - - - - - - - 70 64 107 188 123 87 133 79 20 84 69 111 191 130 93 81 Soil test Cl, lb/a (0-24") 9 16 24 28 14 40 61

Chloride Fertilization on Wheat Grain Yield Chloride Marion Co. Saline Co Stafford Co. Rate Site A Site B Site C Site D Avg. lb/a - - - - - - - - - - - - - - - - - - - - - bu/a - - - - - - - - - - - - - - - - - - - - 45 80 51 89 83 70 73 64 69 20 47 85 54 90 75 74 Soil test Cl, lb/a (0-24") 7 14 22 15 12 *Average over either 12 or 16 varieties. Soil test Cl, lb/a (0-24")

Chloride Fertilization on Grain Sorghum in Kansas Grain Yield   Chloride Marion Co. Brown Co. Osage Co. Rate Site A Site B Site C Site D  lb/a - - - - - - - - - - - - - - - - - - bu/a - - - - - - - - - - - - - - - - - - 87 117 63 92 102 125 88 10 94 139 71 113 106 95 126 20 97 135 72 111 96 Soil test Cl, lb/a (0-24") 9 7 43 52 29

Chloride Fertilizer Recommendation

Iron (Fe)

Iron (Fe) Mitchell Co.

Iron (Fe) Iron in the plant Deficiency symptoms Catalyst in the production of chlorophyll Involved with several enzyme systems Deficiency symptoms Yellow to white leaf color Symptoms first appear on the younger leaves Wide range of susceptibility of different crops Sorghum, field beans and soybeans are more sensitive than corn and alfalfa Varieties differ within crops

Factors Affecting Iron Availability High soil pH. Soils with high salt contents. Cool, wet springs. Poor soil drainage and aeration. Susceptible crops/varieties. High concentrations of nitrate-N inhibit conversion of Fe+++ to Fe++, increasing severity of iron chlorosis.

Fertilizer Sources of Iron Deficiencies occur more frequently than most other micronutrients in Kansas Patchy or irregular appearance in the field Success with iron fertilization is difficult Difficulty in correcting Fe deficiency with soil-applied fertilizer Iron quickly converted to unavailable form. Certain Fe chelate carriers (EDDHA) have been effective but have not been economical and may require multiple applications Foliar Application most promising

Foliar Applications Applications must be done before plants are severely damaged by chlorosis and may need to be repeated Ferrous sulfate (1-2% solution) plus a wetting agent or one of several iron chelates/complexes may be used Critical timing Soybean - by the first trifoliate leaf Sorghum - apply by the 6th leaf stage

Common Iron Fertilizers Fertilizer Source Iron Sulfate Iron Chelates Other Organics Manure - best Fe (%) 19-40 5-12 5-11 ??

Average animal manure micronutrient content of different animal sources Manure source Iron Manganese Boron Zinc Copper -----------------lb/wet ton--------------------- Dairy solid 0.5 0.06 0.01 0.03 Swine solid 19.0 1.09 0.04 0.79 0.50 Poultry 3.0 0.61 0.08 0.48 0.66 -----------------lb/1000 gal--------------------- Dairy liquid 0.9 0.11 0.12 Swine liquid 2.5 0.23 1.03 0.62

Micronutrients of Little Concern Reason Calcium Very acid soils - Rare deficiency Magnesium Very acid, sandy soil Boron Dry, leached, low OM sands – Alfalfa or Soybeans Manganese High pH, High OM Copper High OM, Highly weathered soil Molybdenum Highly weathered acid soils – legumes – enough in seed?

? Kent Martin kentlm@ksu.edu 620-276-8286